Racy and Gory Images Cause Temporary Blindness

Aug. 17, 2005

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Participants in the research were tested to see if they rank high in "harm avoidance," meaning they are cautious and want to avoid situations in which they could be hurt, or if they rank low, meaning they are more carefree and willing to take a risk. So far more than 100 persons have been tested, and the researchers say the results are clear.

The more cautious participants, those who wanted the most to avoid personal harm, suffered more from temporary blindness than those who were more willing to take a chance.

The purpose of the research, of course, is to delve into the workings of the human brain. But there's a practical side to it as well.

Our response to highly emotional stimuli could be dangerous.

"If you take a basic evolutionary type perspective, something that is violent or gory could be a risk to us, and things that are erotic have the potential for procreation," Zald says. So we need to pay attention to both of those, but that imposes some risks.

"It's a trade-off," Zald says. "It's ensuring that we pay attention to this information, but it comes at our cost of failing to see other relevant information.

"In that sort of cost benefit analysis, one suspects that in the past it was beneficial. At our high-paced speed today, it's possible it becomes detrimental."

A terrible traffic accident, for example, may leave us unable to see a child darting into the road ahead of us.

Lee Dye's column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.